Casters have been widely applied to many products that are designed for moving easily. To meet the requirements in the market and of the consumers, casters have been developed from having one simple function of rolling to having many other technical features at the same time, such as being single-braking, double-braking and/or direction-lockable.
FIG. 1 shows a conventional caster 1 for mounting to each of four legs or four lower corners of a wheel-supported hospital bed. As shown, the caster 1 is of the type provided with braking and direction-locking functions, and it mainly includes a wheel 10 and a braking and direction-locking mechanism 11. The braking and direction-locking mechanism 11 includes an upper barrel 110, a special brake block 111 provided in the barrel 110, a pin 112 extended through the brake block 111 for controlling the latter to rotate, and a wheel support 113 connected to a lower end of and freely swiveling relative to the barrel 110. By rotating the brake block 111 to three different positions with the pin 112, the wheel 10 can be set to one of three different operating states, namely, a braked state, a direction-locked state, and a freely swiveling state.
In the braked state, the wheel 10 is stopped from rolling by a stopping means in the wheel support 113, and the wheel support 113 can not freely swivel relative to the barrel 110. In the direction-locked state, the stopping means in the wheel support 113 is released, so that the wheel 10 can roll while the wheel support 113 can not freely swivel relative to the barrel 110, restricting the wheel 10 to roll and move in a fixed direction. In the freely swiveling state, the wheel 10 can roll and the wheel support 113 can freely swivel relative to the barrel 110.
FIG. 2 shows the caster 1 shown in FIG. 1 is usually connected to a caster control mechanism 2 for use. As shown, the caster control mechanism 2 includes a first control lever 20, a second control lever 21, an axial shaft 22 extended between and connected to the first and the second control lever 20, 21, a first pivoting rod 23 provided near each of two opposite ends of the axial shaft 22, two transverse shifting bars 24 coaxially connected at respective inner end to each of the first pivoting rods 23, and a second pivoting rod 25 connected to an outer end of each of the transverse shifting bars 24. Finally, four casters 1 are separately connected at the pins 112 to the second pivoting rods 25.
The first and the second control lever 20, 21 have three different operating positions. The first operating position serves to control the casters 1 to a freely swiveling state, the second operating position serves to control the casters 1 to a direction-locked state, and the third operating position serves to control the casters 1 to a braked state.
With the conventional caster control mechanism 2 provided below the hospital bed, a user may step any of the first and the second control lever 20, 21 for setting the casters 1 to the freely-swiveling state to move in any direction, or to the direction-locked state to move in one fixed direction, or to the braked state to immovably stand on floor.
However, since the conventional caster control mechanism 2 is provided below the hospital bed, it is possible the first and the second control lever 20, 21 are unexpectedly contacted by someone and changed into a non-desired operating state. On the other hand, the first and second control levers 20, 21 have three different operating positions. For a user who is not experienced in operating the wheel-supported hospital bed, it is uneasy to quickly switch the casters 1 to a desired operating state via the control levers 20, 21. Thus, the conventional caster control mechanism 2 and the conventional caster structure 1 are not so convenient for use.
It is therefore tried by the inventor to develop an improved power-operated caster brake mechanism to overcome the disadvantages of the conventional caster control mechanism 2 and the conventional caster structure 1.